10 Market Bubbles That Could Soon Burst

The president of the Minneapolis Federal Reserve, Navayana Kocherlakota, recently published a paper in which he argues that government guarantees helped fuel the bubble in real estate. While his paper was largely aimed at prescribing solutions to this problem, it raises the question: What other bubbles are lurking out there in the global economy? We asked several experts and to our surprise, they had a long list:

1. Gold: The price of gold bullion has risen from $294 an ounce in 1998 to $1,404 last week, an increase of 377%. "It's the biggest, baddest bubble of them all," says Robert Wiedemer, author of Aftershock: Protect Yourself and Profit in the Next Global Financial Meltdown. Gold has no intrinsic value. A telltale indicator that gold is a bubble: incessant cocktail party chatter about buying gold and endless TV commercials offering to buy gold jewelry. The SPDR Gold Trust ( GLD) ETF is up 28% since the beginning of the year.

2. Real estate in China: Chinese real estate prices are up only 9.1% this year, which may seem more frothy than bubbly. But rising prices are generating rising demand, which is a clear sign of a bubble, says Vikram Mansharamani, whose book, Boombustology: Spotting Financial Bubbles Before They Burst, will be published early next year. The participation of amateur investors like waiters and maids in the property boom is a clear sign of a property bubble in China. The fact that developers are building more apartments than there are buyers is another giveaway.

3. Alternative energy: Solar technology is still uneconomic, yet governments all over the world are subsidizing solar energy firms. "There are plenty of people who shouldn't be in the solar energy industry who are," says Mansharamani. Do we really need 250 venture-capital-backed solar cell companies? The Market Sectors Solar Energy ( KWT) ETF had a 100% gain this year, before dropping back.

5. Apple ( AAPL): OK, everybody loves their iPad and iPhone (except if they live in New York or San Francisco, where signal strength is a problem). But Apple shares are up 1,200% since 2001, which has to come close to being the definition of a bubble. "Apple is a high-fashion company," says Wiedemer. "If CEO Steve Jobs either leaves or dies, I think they will have trouble maintaining that incredible fashion sense, and as such it's time will go," he says.

6. Social networking: Sure, Facebook has 500 million members, but what is that worth? Some estimates put the company's market value as high as $35 billion, but shares in these social networking companies are not listed and are so far only traded by a few insiders. Twitter, with almost no income, is said to be worth $1.5 billion, and LinkedIn is also estimated to be trading at a market value of $1.4 billion. "There aren't any anchors or valuation methods to guide investors in terms of valuation," says Mansharamani. "When you have that lack of clarity, almost anything is possible." Many in the tech world try to figure out what these companies might be worth some day far in the future and then discount that back to some reasonable price today. Remember Boo.com?

7. Emerging market stocks: As an asset class, these shares have risen 146% in the past two years. "We're only halfway along the way to a gigantic eventual bubble in the emerging markets," says Barton Biggs, the former Morgan Stanley Asset Management chairman who accurately predicted the U.S. stock market bubble in the late 1990s. These countries, such as Indonesia, Australia, Russia and Brazil, are growing wildly even though there's no growth in the world economy. Much of their gains is backed by commodity prices, which are also a bubble (see item No. 4). "I have every reason to believe this will turn into a bubble," says Mansharamani.

9. The U.S. dollar: Although the dollar is down 10% against the euro so far this year, Wiedemer believes the greenback is firmly in bubble territory. He believes it will pop when foreigners stop buying U.S. assets such as stocks and bonds. "Foreigners say, 'I'm worried about inflation -- you're going to pay me back in dollars worth less than when I invested'." While China may hold its dollar bonds forever, he says, pension funds in Japan and insurance companies in Europe will start dumping dollars as U.S. inflation climbs.

10. U.S. government debt: "When this bubble pops you're out of bubbles -- nothing is too big to fail any more," says Wiedemer. The debt bubble is growing very rapidly and will continue to grow, he says. Basically, there's no way the U.S. government can ever pay back the $13.7 trillion it currently owes (mainly to foreigners), and eventually they will stop buying. The bubble pops when the government has trouble selling its debt -- just like Ireland and Greece are experiencing at the moment. Instead of borrowing money, the government starts printing money, which is what's happening now. The Fed's balance sheet has gone from $800 billion in 2008 to $2.2 trillion, and the central bank just announced it was printing another $600 billion. Says Wiedemer: "The medicine starts to become poison."